Opposition proceedings are the only way to request the cancellation or limitation of a patent that has already been granted. The opposition of a European patent can be carried out through an administrative procedure before the EPO, where it is assessed by a specific division of the office.
For an opposition to be effective, it must follow defined rules and timelines: for example, the opposition must be filed within nine months from the date the grant of the patent is published, and any third party may file an opposition against a European patent.
The effects of the opposition procedure - confirmation, limitation or cancellation of the patent as granted - will apply to all national patents that derived from the European patent. In Italy, there is no opposition procedure for patents before the Italian Patent Office.